Thanks! Going to try to take care of it this weekend. :-)

never use muratic acid on natural stone! there is a product made by Prosoco called Vanatrol, it is made to soften and remove mortar without bleaching out all the beautiful natural stone colors.

Here is a link that might be useful: Vana Trol link

Since no one answered your question directly, you can get muriatic acid in any pool supply store. Make sure to read EVERYTHING about it before you play with it. Do a test run in a place where it is not going to be too visible if it turns out to be damaging on the learning curve. Have plenty of protective gear, lock your pets away, have your kids go to grandma's, protect any vegetation that you don't want to end up dead. Have a plastic bristle brush ready to scrub the bubbles off to see the results before you wash it off. It's a lot to think about, but it can be very rewarding if it is done well. I work in the office for a Construction and Maintenance Company here in Los Angeles and based on the hands of the guys that do only this kind of jobs I'd say that those jobs are not for do-it-yourselfers. But by looking at how they do it and how nice and clean concrete surfaces became, I bought the materials and did my own driveway and it turned out to be like new!

Here is a link that might be useful: Look up acid wash on this website.

i work with all different types of stone, bricks, pavers, concrete - and using muratic acid to clean natural stone and bricks is 100% safe(for the stone), if done correctly. i usually mix it with warm water at a lower ratio(more diluted then recommended) and it works great with a wire brush or stiff bristle natural fiber dustbrush. i dont know a brick/stone mason that doesnt acid wash every job after setting and pointing.

It bleached all my stone on my pool waterfall !

Don’t use Muriatic Acid on your stone! You will ruin it.

You just need a masonry acid cleaner, nothing exotic. Any construction yard has it.

Dilute it, splash the whole perimeter with clean water, do the scrub fast, then rinse like crazy. If leaves get hit they spot or curl but the plant itself usually recovers. I’ve done it twice and only lost one tiny sage plant, which was already looking sad, so… yeah.